Termite guts could provide a way to produce biofuel from woody biomass

Mike Scharf's work with termites has shown that the insects' digestive systems may help break down woody biomass for biofuel production (Image: Purdue Agricultural Communication photo/Tom Campbell)

Ethanol is the most commonly used biofuel worldwide and is made by fermenting the sugar components of plant materials, usually sugar and starch crops such as sugar cane, corn and wheat. The difficulty in accessing the sugars contained in woody biomass, coupled with criticism that the use of food crops for biofuel production has a detrimental effect on the food supply has prompted research into biofuels that can be made from cellulosic biomass, such as trees and grasses. By looking at the digestive system of termites, researchers have now discovered a cocktail of enzymes that unlocks access to the sugars stored within the cells of woody biomass that could help make it a more viable source of biofuels, such as ethanol.

Until now, a rigid compound that makes up plant cell walls known as lignin has been one of the most significant barriers blocking the access to sugars contained in biomass and inhibiting their use in fuel production. Looking for a way to break down this barrier, Mike Scharf, the O. Wayne Rollins/Orkin Chair in Molecular Physiology and Urban Entomology at Purdue University, and his research partners turned to that scourge of the homeowner, the termite. Their study was the first to measure the sugar output from enzymes created by the termites themselves and the output from small protozoa called symbionts, which live in the termite guts and aid in digestion of woody material.

"For the most part, people have overlooked the host termite as a source of enzymes that could be used in the production of biofuels. For a long time it was thought that the symbionts were solely responsible for digestion," Scharf said. "Certainly the symbionts do a lot, but what we've shown is that the host produces enzymes that work in synergy with the enzymes produced by those symbionts. When you combine the functions of the host enzymes with the symbionts, it's like one plus one equals four."

The researchers separated the termite guts, testing portions that did and didn't contain symbionts on sawdust to measure the sugars created. Once they identified the enzymes, they worked with a protein production company to create synthetic versions. To do this, they inserted the genes responsible for creating the enzymes into a virus and fed it to caterpillars, which then produced large amounts of the enzymes.

They found that the three synthetic enzymes act on different parts of the biomass. Two are responsible for the release of the sugars glucose and pentose, while the third breaks down lignin, a complex chemical compound in the walls of plant cells that provides mechanical strength to the cell wall, and by extension the plant as a whole. Working in combination, the synthetic versions of the host termite enzymes were shown to be very effective at breaking down the woody biomass and releasing sugar.

"We've found a cocktail of enzymes that create sugars from wood," Scharf said. "We were also able to see for the first time that the host and the symbionts can synergistically produce these sugars."

Next, Scharf said his laboratory and collaborators would work on identifying the symbiont enzymes that could be combined with termite enzymes to release the greatest amount of sugars from woody material. Combining those enzymes would increase the amount of biofuel that should be available from biomass.

The team's findings have been published in the early online version of the journal PLoS One.

Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag. All articles by Darren Quick

Just think, one day in the future your petrol tank is on empty so you go out and mow your lawn so you can fill your car. I like the sound of that

Daniel Spinks 7th July, 2011 @ 09:39 am PDT

Would be nice - if biofuels were necessary, instead of a payday for agro lobbyists.

We have such huge quantities of oil and natural gas that there's plenty of time to perfect the tech we already have underway; improved nuclear, and battery tech for cars.

But this is all decided by personal politics. There are so many ignoramuses that believe that you can 'wish' something into generating efficient power (windmills anyone)?

Todd Dunning 7th July, 2011 @ 11:19 am PDT

The termite can eat wood but it cannot digest it. The small protozoa called symbionts can digest it but it cannot eat it. Neither can survive without the other. So I have always wondered if everything evolved upward in sequence - which evolved first? And then - how did the other survive until they met? What was the protozoa before it miraculously became a life sustaining host? There are thousands of examples like this and some even requiring multiple reliance in order to survive. This appears to be the opposite of the survival theory but rather and interdependence between creatures and harmony between them.

donwine 7th July, 2011 @ 05:21 pm PDT

You can always tell those who are either not well read or not confident in their views. Typically they will be derogatory, using terms like "ignoramus" to describe those who disagree.

But for those who read and think, biofuels do in fact have a role to play in our current supply. There are many reasons, but the two dominating factors are the predicted (inevitable?) increase in transportation fuels and ability for non-fossil rich countries to have more control over their livelihood and their futures, to a degree. Regardless of the debate about the actual deposits available, we are reaching a point where better technology and greater effort is required to mine/acquire natural gas and oil. We should continue on that path, for certain. But we must also have a good grip on our alternatives and be able to supplement as needed, preferably in an increasing amount over time. In the U.S., the ability to ramp up biofuel production is a powerful hedge against ANYONE who supplies us, even the Canadians (yes, they are quite friendly, but...). And for less developed nations that otherwise would be 100% dependent on oil and gas imports, growing feedstock provides huge, double benefits. It gives them some domestic fuel source and it could be the catalyst to drag them out of a hole into the world of newly developed nations.

But, if you only car about yourself, all of this may be moot.

John Sullivan 8th July, 2011 @ 06:56 am PDT

More than half the energy used is wasted in moving fruit from South America or seafood from Asia to the USA or heating under insulated homes and buildings or using a 3,000 pound car and 6 gallons of gas to transport one person to work or school and back home. All that the push toward biofuels has done is further enrich executives and shareholders at companies like Archer Daniles Midland while nearly doubling the cost of food during the period from 2004 to 2007 alone.

Billions are going hungry so that Americans can drive their SUV's at 80mph down the highway often pulling their 200hp bass attack boat or a 30 foot "Wilderness" trailer or simply driving to nearest Starbucks to get a cup of coffee (when they could have made a better cup of coffee at home).

Instead of spending trillions of dollars to kill people in the Middle East we should be investing in mass transit and energy efficiency and creating jobs instead of amputees in the USA. Not nearly as profitable for Lockheed Martin, Blackwater, or the Bush families and friends, but a lot better for the working people of this country and a lot better for the people of the rest of the world who would like us to take our bombers and tanks and soldiers and just go home and leave them in peace.